Fuel cells are electrochemical devices that continuously convert chemical energy into electric energy for as long as fuel and oxidant are supplied. Different categories of fuel cells are known, including proton exchange membrane fuel cells (PEMFCs) and solid oxide fuel cells (SOFCs) which are both fueled by hydrogen. SOFCs can also be fueled by other fuels such as carbon monoxide, natural gas and other hydrocarbons. The primary advantages of fuel cell power generation include increased efficiency, lower weight and smaller size, less air pollution, and reduced noise.
Fuel cells are being considered for use in many different applications. For example, they may be used to power automobiles such as passenger cars and light-duty trucks, and naval vessels including surface ships and submarines. NASA envisions employing SOFCs running on jet fuel reformate for its Uninhabited Aerial Vehicle (UAV) and Low Emission Alternative Power (LEAP) missions as well as for transatlantic and intercontinental commercial airline flights. The U.S. military is also considering the use of fuel cells that are fueled by jet fuel reformate.
The jet fuel is subjected to a reforming process in a fuel processor to produce hydrogen-rich reformate. However, depending on the source and kind, jet fuels are invariably sulfur-laden to the extent of about 0.3-1.0 weight percent. Coal, another logistic fuel and available in plenty also contains sulfur (as organosulfur) as high as 3%. The sulfur poisons the reforming catalyst used in the reforming process. Also, when sulfur is present in the fuel used in a fuel cell, it poisons the fuel cell anode and thereby degrades the performance of the fuel cell.
Therefore, it is necessary to pay close attention to these sulfur compounds when the desulfurization is considered in the fuel pre-processing device.
In addition, it would be desirable to provide improved sulfur sorbents.